Arsmirandite is a rare volcanic mineral discovered in the fumaroles of the Tolbachik volcano in Russia. It typically appears as small, bright yellow to yellowish-dark grayish green to olive-greenish black platy crystals associated with other fumarolic minerals in high-temperature environments.
Is this arsmirandite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch arsmirandite with a known reference. Arsmirandite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: grayish green with olive hue.
- 3Read the lusterHold the specimen under a strong light. Luster: strong vitreous.
- 4Match the color rangeCompare against the expected color range: dark grayish green, olive-greenish black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals.
Often confused with
Arsmirandite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside arsmirandite
Minerals reported to co-occur with arsmirandite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₁₈Cu₁₂FeO₈(AsO₄)₈Cl₅
- Mohs hardness
- 2-3
- Density
- 3.715 g/cm³
- Colors
- Dark grayish greenOlive-greenish black
- Streak
- Grayish green with olive hue
- Luster
- Strong vitreous
- Transparency
- Translucent to nearly opaque
- Crystal system
- Monoclinic
- Crystal habit
- Platy crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A sublimate around an active volcanic fumarole
Where rockhounds find arsmirandite
Classic worldwide localities
- Arsenatnaya fumarole, Second scoria cone, Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia
Field-hunting tip
Where it forms: A sublimate around an active volcanic fumarole. If you start seeing lehmannite, hematite, sanidine in float, you are in the right ground. Typical habit: platy crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify arsmirandite?+
Where is arsmirandite found?+
Is arsmirandite safe to handle?+
What rocks look like arsmirandite?+
What minerals are found with arsmirandite?+
What kind of rock does arsmirandite form in?+
What is arsmirandite used for?+
Find arsmirandite on the map
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